Treatment of hydrocarbons



July 17, 1923. 1,462,247

I w. F. RITTMAN TREATMENT OF HYDROCARBONS File e 1917 2 Sheets-Sheet 1WQMNJWWM WWW July 17, 1923. 1,462,247

' w. F. RITTMAN TREATMENT OF HYDROCARBONS Filel Feb. 5, 1917 2Sheets-Sheet 2 WITNESSES INVENTOR Patented July 17, 1923.

UNITED STATES PATENT -TJFFICE.

WALTER F. RITTMAN, 0F PITTSBURGH, PENNSYLVANIA.

TREATMENT OF HYDROCARBONS.

Application filed February To all whom it may concern:

Be it known that I, WALTER F. Rrrr MAN, residing at Pittsburgh, in thecounty of Allegheny and State of Pennsylvania, a citizen of the UnitedStates, have invented or discovered certain new and useful Improvementsin the Treatment of Hydrocarbons, of which improvement the following isa specification.

In the cracking of heavy petroleum hydrocarbons for the production oflow boiling hydrocarbons, it is desirable that a process or method ofoperation be available whereby all types of petroleum oils boiling abovethe highest boiling point of the loW boiling material desired to beproduced, can be used instead of only certain types of high boilinghydrocarbons such as gas 011 and heavy fuel oil. Heretoforc it has beenproposed to decompose or crack high boiling hydrocarbon products, suchas those boiling above 27 5 C. in a still under pressure, and variousmethods of accomplishing this result have been proposed. Such operationsare subject to the inherent difficulty of raising relatively low boilingoils, such as kerosene, etc., to an eificient cracking temperaturewithout such a corresponding increase in pressure as to be beyond thelimits of a still to withstand. As the commercially effective crackingtemperature is generally in excessof 400 0.,

the difiiculty and danger incident to raising the oil having a boilingpoint at and below 275 C. to a cracking temperature in a still, will beclearly appreciated when it is recalled that to raise the temperature ofwater from 100 C. (its boiling point at atmospheric pressure at sealevel) to 200 C. re-

quires a pressure of about 212 pounds. By reason of the operativedangerand difliculty above stated, more than one-fifth of crude petroleumcannot be treated by procemes above referred to.

It is well recognized in the art that in all pressure distillationprocesses today in operation, oils with a. Baum gravity lighterthanabout 36 cannot be held in the-still until their boiling temperature isincreased to above cracking temperature. -Theoretically, at lea-st,these oils can be held in the still until their cracking temperaturesare below their boiling temperatures, but the practical limits of thematerial entering into the construction of the stills used for thispurpose, have made it impractical to date,

5, 1917. Serial N0. 146,719.

ing temperature is lower than the b0iling temperature and the oil cracksbefore it boils. This invention recognizes this limitation of pressuredistillation processes and through stage two, wherein the relativelylighter oils, just referred to, are treated in the gaseous phase, Wherethe question of boiling point has no relation to the physical strengthof apparatus necessary, this limitation is avoided.

The present invention is a process involving two separate and distinctstages of cracking. In one stage, the oil in the form of a liquid in thepresence of large quantities of gaseous products from the cracking ofthe same liquid (i. e. a two phase sys tem) is subjected to atemperature in excess of 300 C. and a pressure of 30 or more pounds persquare inch; and in the other stage, the relatively low boilinghydrocarbone, but not sufliciently low boiling to be commercialgasolene, given off from stage one, are subjected while in a singlegaseous phase, and where the liquid phase is substantially absent, to atemperature in excess of 400 C. and toa pressure in excess of 30 poundsper square inch. Opinions among petroleum technologists vary regardinthe,

cracking of petroleum where both liqui and gases are present as in apressure distillation process, as to whether cracking occurs in only theliquid subjected to the highest temperature and where one wouldnaturally believe that practically all cracking took place, or whethercracking takes place both in the liquid and in the vapors above thepressure in excess of 30 pounds per square V inch, at high or crackingtemperature and provision is made for segregating from the hydrocarbonsformed in the still those having a boiling point at or below gasolene,i. e.,up to 150 degrees to 200 degrees (3., and for the re-treatment ofa portion or all of the other hydrocarbons from the still, in a singleor gaseous phase, forming the other stage of the process describedherein.

In the practice of the invention, means for operation. are providedwherein crude oil, from which the low boiling parts have not beendistilled, may be introduced lIltO" the distillation apparatus and thedistillation carried on in the ordinary manner at atmospheric pressureuntil the desired low boilingparts have been removed. The distillationis then proceeded with under pressure and further low boiling productsproduced through cracking of the still contents. If desired, as soon asthe gasolene is distilled ofi", materials boiling just above gasolene,but too volatile to be held in the cracking still, can be fed to thecracking retorts wherein the distillate'is vaporized and cracked intolower boiling hydrocarbons. Pressure is then applied to the still sothat the boiling temperature of the hydrocarbons will be sufficientlyhigh to effect cracking in the still, i. e., cracking in a single andgaseous phase will then come into operation and from. that time forwardboth stages will operate simultaneously but successively.

It is characteristic of this invention that the relative advantages ofthe pressure-distillation method of cracking and the vaporphase crackingare so combined as to bring about a continuous operation in which thematerial or materials to be cracked move progressively from the. onemanner of cracking to the other. In the pressure distillation stage ofthis invention, very large volumes of material (as high as 1000 bbls. ofoil) are subjected in a mass to cracking treatment for relatively longperiods of time (i. e. from 20 to 50 hours) until the maximum yieldsfrom the entire body have been obtained, whereas in the vapor-phasecracking only very small quantities, as for example, gallons, aresubjected to treatment at any one period of time and then only for a fewseconds. Approximately the same capacities over a long period of timeare attained in these two stages, but with diverse methods of treatment.In thepressure-distillation cracking stage, the material will becomeprogressively heavier as the cracking proceeds, one method of operationhereinafter described, permits of the return to the still of the heavierparts for further cracking, until the operation is completed, when theresidue is removed and another still connected. Where desired, the heavyparts of the first pressure-still cracking may be returned to a separatestill. In the vapor-phase cracking the material to be cracked while in avaporous state, is continuously maintained of uniform composition, sinceall the cracking possible in a single operation is accomplished by thesingle passage of such vapors from the retort under suitable crackingconditions.

In the accompanying drawings forming a part of: this specification, Fig.1 is a view in elevation, illustrating a form of apparatus adapted forthe practice of the invention described herein; Fig. 2 is a similarview, showing a plant embodying a plurality of cracking stills andretorts; Fig. 3 is an elevation showing a modification of the plant.

In the practice of the invention, the raw oil to be treated is chargedinto a still 1 of any desired type and adapted to be heated by any ofthe known or suitable means employed for that purpose. From the stillextends a pipe 2 which may be made of such size and length as to effecta condensation of the higher boiling products formed in the still, butit is preferred that the pipe be connected to a fractional condenser 3of any suitable type or construction adapted to effect a condensation ofthe heaviest products formed. The condensate from this condenser 3passes into a tank 4. If in the condenser 3 only the heaviest productsare condensed out, and discharged into a tank 4, the latter may beconnected by a pipe 5 to a still 1, a preheater being preferablyarranged in the pipe 5. But if the condenser 3 is so operated as tocondense out all the hydrocarbons except those adapted to form thedesired end product, i. e., one having a boiling point at or below 150to 200 0, then the tank 4.- will be connected by a pipe 7 to a retort 8.In case the condenser 3 is so operated as to segregate only the heaviestproducts which it is undesirable to retreat in a single stage or-gaseousphase, the remaining vapors would pass to a second condenser 9 in whichproducts adapted to gaseous phase retreatment are condensed out anddischarged into a tank 10 which is connected to the pipe 7 The vaporsdischarged from the condenser 9 will flow into the condenser 11, wherethey are condensed. The liquids flowing through the pipe 7 may, ifdesired, be preheated and then forced into the retort 8 where they willbe subjected to conditions of temperature and pressure and for a periodof time suitable for the formation of the desired end product, asdescribed and claimed in applications Serial Number 29020, filed May18th, 1915, and 85603 filed March 24th, 1916. If desired,

the raw material may be first treated in the retort 12 in the mannerabove described and then that part of the product formed in the retort,having a boiling point above, say 275 C. and segregated from otherprodnets in condensers 13 or other suitable means, may be charged intothe still 14 and cracked under pressure, the vapors result ing from thedistillation and cracking being condensed in the usual or any suitablemanner.

I claim herein as my invention:

The process herein described for forming a low boiling hydrocarbon froma high boiling hydrocarbon which consists in cracking the high boilinghydrocarbon, segregating from the products of cracking the end productdesired and then cracking the remaining hydrocarbons, one of thecracking operations consisting in subjecting the hydrocarbons in arelatively large liquid mass, to heat and pressure suitable for theproduction of the end product desired, segregating such end product, andthe second operation consisting in vaporizing the material remainingafter such segregation and subjecting such vapors to heat and pressureand for a period of time suitable for the formation of the desired endproduct.

In testimony whereof, I have hereunto set my hand.

WALTER F. RITTMAN.

